Transit Temperatures of California Lettuce

Excerpts from the report: The ideal temperature for maintaining quality in lettuce during marketing is 32 F. As the temperature rises above this optimum, soft rot decay increases, physiological disorders such as russet spotting 3 appear, and aging from natural respiratory processes is accelerated. When western lettuce is shipped to eastern markets, the time spent in transit accounts for most of the period between harvest and consumption. Significant departures from the optimum temperature that result from inadequate precooling of the lettuce or from insufficient refrigeration in transit and at the market can cause substantial wastage. The development of new railway equipment makes testing desirable to determine the effectiveness of the equipment in providing suitable transit temperatures. Multipurpose, mechanically refrigerated cars and ice-refrigerated cars equipped to give thermostatically controlled temperatures are now being constructed. Some are already available to shippers of perishable commodities. For these reasons, an accompanied lettuce transportation test was conducted from California to New York City in August 1957 to determine the effect of salting practices, size of load, pattern of loading, type of container, and type of railway equipment on transit temperatures of uniformly precooled lettuce. Studies were also conducted to relate the transit temperatures obtained in these tests to disorders and quality of the lettuce on the market. The studies are part of a broad program of continuing research designed to reduce the cost of marketing farm products.